In the food industry, it is common to pre-cut various food products, such as meats, before the food products are dispensed to the consumer. As an example, pork chops are commonly cut from a pork loin and marketed to the consumer individually or in packages with a plurality of pork chops in each package.
Various automated systems have been constructed to perform the task of pre-cutting food products, such as meats, to create individual items for the convenience of the consumer. For example, an apparatus could cut pork chops having a consistent thickness resulting in multiple pork chops having a constant thickness.
However, some food products, including pork loins, have a non-uniform cross-sectional area. The shape of a pork loin is not uniform over its length. A pork loin can be bigger or smaller at one end or the other and may vary in cross-sectional area along its length. As progressive cuts made in the pork loin, the cross-sectional area of the pork loin may vary. Thus, successive pork chops cut from a pork loin may be larger or smaller depending upon the actual cross-section of the pork loin where the pork chop is cut. Thus, cutting a plurality of items (e.g., pork chops) from a food product (e.g., a pork loin) with a constant thickness may result in successive pork chops which can vary significantly in weight.
Food products may be sold by weight. Thus, if the weight of individual pork chops vary, the collective of weight of a package of pork chops may also vary. However, since the package of pork chops is being sold to the consumer by weight, different packages of pork chops (all containing the same number of pork chops) may have different prices. The consumer may then need to select accordingly and purchase a package of pork chops reasonably matching the consumer's expectations.
Food products may also be sold by number of items. For example, a package of pork chops may be sold as a package containing a predetermined number of pork chops irrespective of the weight of an individual pork chop. Since the weight of individual pork chops may vary, the weight of a package of a predetermined number of pork chops will also vary. This may result in the consumer getting more or less (weight) depending upon which package is purchased. Thus, differing packages may be more or less desirable for the consumer to purchase.
However, food products may also be sold requiring a precise number of items and a precise weight for those items, either collectively or individually. This dual requirement will not allow a significant variation in weights among the individual items.
Since the cross-section of a food product, e.g., a pork loin, may vary but the weight of each individual item, e.g., pork chop, must stay the same, then the thickness of each individual item must either vary or another operation must be accomplished following the cutting in order to adjust the weight of each individual item. For example, trimming of the edges of a cut pork chop may be done in order to reduce the weight of each pork chop to be consistent among pork chops. However, not only is manual trimming time-consuming but it also results in a significant amount of wasted material.
Prior art optical systems have been employed to attempt to determine the size of a product being cut and to adjust the thickness of the cut in order to control the weight of each individual item being cut.
U.S. Pat. No. 5,267,168, Antonissen et al, Apparatus For and Method of Controlling Slicing Machine, discloses a slicing machine which includes a control system having a camera which views a cut face of a product being sliced. The processing of the image data includes classifying the image data by comparison with an intensity threshold which is varied automatically in accordance with the populations of data and the different classes. A source of illumination (7) is positioned below the face of the product (3) being cut by blade (1). A camera (6) is also set at an angle with respect to the face of the product (3) being cut by blade (1). The source of illumination (7) illuminates the entire face of the product (3) being cut at one time and the camera (6) senses light from a general area facing the product (3) being cut which includes light from the source of illumination (7) being reflected.
U.S. Pat. No. 5,054,345, Weber, Method of Obtaining Constant Weight Portions or Slices of Sliced Food Products, discloses a method for obtaining constant weight portions or slices from sliced food products where, in each case, individual slices or portions of several slices with exactly predeterminable weight can be formed in real time operation during the cutting process by detecting the cut surface area, taking account of the specific weight and computing of the required feed of the product. A light source (52) is set at an angle α with respect to surface (48) of ham (10). The light (54) remitted or diffusely reflected from surface (48) falls as light beam (54) onto video recorder (56) arranged at an angular specular reflection angle β also with respect to surface (48) of ham (10). Again, the light source (52) illuminates the entire surface (48) of the ham (10) and the video recorder (56) records light including light being reflected from surface (48) of ham (10).
A problem with optical systems intended to determine the cross-sectional area of the food product to be cut is that it is difficult for the sensor to determine what light is reflected from the food product and what light is ambient or is reflected from background clutter. Some systems use an amplitude threshold to filter the incoming light signals. However, ambient light or light reflecting from the background may still be of sufficient amplitude to interfere with a proper determination of the cross-sectional area of the cut face of the food product.